On the Moduli Dependence of Nonperturbative Superpotentials in Brane Inflation

We discuss string corrections to the effective potential in various models of brane inflation. These corrections contribute to the mass of the inflaton candidate and may improve its slow-roll properties. In particular, in orientifold string compactifications with dynamical D3- and D7-branes, the corrections induce inflaton dependence in the part of the superpotential that arises from gaugino condensation or other nonperturbative effects. The additional terms are in part required by supersymmetry. We explicitly discuss D3/D7-inflation, where flat directions of the potential can be lifted, and the KKLMMT model of warped brane inflation, in which the corrections open up the possibility of flattening the potential and canceling unwanted contributions to the inflaton mass.